In order to provide cardiac imaging for a patient, an imaging device (such as a magnetic resonance device in particular) must be synchronized with a cardiac signal of the patient. An ECG measuring device which has a sensor unit for capturing cardiac signals is customarily used for this purpose. The sensor unit comprises a plurality of ECG electrodes, which are placed on the patient in the chest region. A trigger signal for the cardiac imaging is then generated on the basis of the ECG signals that are captured.